1. Field of the Invention
The invention relates to a method of fabricating a display panel and a method of relocating a display panel, and more particularly to those methods including a step of relocating display panels from a first cassette to a second cassette.
2. Description of the Related Art
Electronic devices are generally designed to include a display panel for displaying an output. A liquid crystal display among display panels is in particular widely used for a personal computer, a word processor and other similar apparatuses because of small power-consumption, small thickness, light weight, and ability of being driven at a low voltage.
FIG. 1A is a perspective view of a liquid crystal display panel, and FIG. 1B is a cross-sectional view of the liquid crystal display panel illustrated in FIG. 1A.
The illustrated liquid crystal display panel is comprised of a thin film transistor (TFT) substrate 1 composed of glass, a color filter substrate 2 composed of glass, and a sealing material 3 coupling the substrates 1 and 2 to each other so that there is formed a space in the range of 5 to 6 xcexcm therebetween. Liquid crystal is sealed within the space between the substrates 1 and 2.
As illustrated in FIG. 1B, the sealing material 3 is formed at a lower edge thereof with a cutout 4 through which liquid crystal is introduced into the space.
FIG. 2 is a flow chart of a method of fabricating a liquid crystal display panel.
First, a glass substrate is subject to steps 201 of washing, drying, printing of an alignment film, rubbing, printing of a sealing material and other necessary steps to thereby fabricate the TFT substrate 1. Another glass substrate is subject to steps 202 of washing, drying, printing of an alignment film, rubbing, distributing spacers and other necessary steps to thereby fabricate the color filter substrate 2.
The thus fabricated TFT substrate 1 and color filter substrate 2 are coupled to each other so that a gap is formed therebetween, in step 203.
The coupled substrates 1 and 2 are diced in step 204 into a plurality of liquid crystal display panels having a size, for instance, in the range of 12 to 15 inches. The dicing step 204 is comprised of the steps of scribing both the TFT substrate 1 and the color filter substrate 2 by means of a diamond cutter, applying impact to the scribed substrates 1 and 2, and separating the substrates 1 and 2 into liquid crystal display panels along scribed lines.
The thus separated liquid crystal display panel has such a shape as illustrated in FIG. 1A.
Then, liquid crystal is introduced into a gap formed in each of the thus fabricated liquid crystal display panels, in step 205. The step 205 is carried out as follows.
First, as illustrated in FIG. 3, a plurality of liquid crystal display panels P and a container containing liquid crystal 10 therein are put in a vacuum chamber 12. Then, air in the vacuum chamber 12 is exhausted.
When a pressure in the vacuum chamber 12 lowers to a sufficient degree, the liquid crystal display panels P are immersed into the liquid crystal 10 through the cut-outs 4. Thereafter, air is introduced into the vacuum chamber 12 to thereby raise a pressure in the vacuum chamber 12 to an atmospheric pressure. As a result, the liquid crystal 10 is introduced into gaps in the liquid crystal display panels P due to capillarity and a difference in an internal pressure between the liquid crystal display panels P and the vacuum chamber 12.
After the liquid crystal 10 has been introduced into gaps in the liquid crystal display panels P, the cutouts 4 are closed in step 206 to thereby hermetically seal the liquid crystal display 10. For instance, the step 206 is comprised of sweeping the liquid crystal, coating resin sensitive to ultra-violet ray, and radiating ultra-violet ray.
Thereafter, steps of polishing, attaching a deflecting plate, making inspection and so on are carried out, and thus, there is completed a liquid crystal display panel.
In the above-mentioned steps, cassettes are employed for containing, transferring and processing display panels in each of the steps 204 to 206. In general, cassettes employed in each of the steps are designed to have the same shape. The reason why cassettes having the same shape are employed in those steps is that if a cassette has to have different shapes for different liquid crystal display panels, it would not be possible to automate fabricating liquid crystal display panels, because liquid crystal display panels have different sizes.
If liquid crystal display panels having different sizes are to be fabricated in a fabrication line, those liquid crystal display panels are contained in a cassette by moving a partition plate in a cassette to thereby conform the cassette to the liquid crystal display panel in size.
However, the above-mentioned method of fabricating a liquid crystal display panel is accompanied with the following problem.
In these days, a liquid crystal display panel has been requested to be large in a size because of variety in fields in which a liquid crystal display panel is used, and to have a smaller gap in order to ensure a wider angle of visibility and enhancement in responsibility. A larger size and a smaller gap in a liquid crystal display panel cause a step of introducing liquid crystal per a unit number of panels to take longer time than other steps. For instance, with reference to FIG. 2, the step 205 of introducing liquid crystal takes time four to five times greater than time which the step 204 or 206 takes. Hence, it is quite necessary to shorten time which the step 205 takes.
In order to shorten time the step 205 takes, the number of apparatuses for introducing liquid crystal may be increased, for instance. However, those apparatuses are expensive. In addition, if those apparatuses are newly introduced into a fabrication line, a fabrication line and/or other fabrication steps might be modified accordingly.
Japanese Unexamined Patent Publication No. 7-153816 has suggested a method of relocating a substrate, comprising the steps of supporting one of substrate vertically standing in a first cassette, at side edges thereof, taking the substrate out of the first cassette, and vertically inserting the substrate into a second cassette.
Japanese Unexamined Patent Publication No. 2-122647 has suggested an apparatus for relocating a semiconductor wafer, comprised of a first wafer carrier containing a plurality of semiconductor wafers, a second wafer carrier containing no semiconductor wafers, a lift arm which lifts a semiconductor wafer up through a bottom of said first and second wafer carriers, and a clamping arm which clamps a semiconductor wafer upwardly lifted by said lift arm. The lift arm raises and lowers, and the clamp arm laterally moves to thereby relocate semiconductor wafers from the first wafer carrier to the second wafer carrier. The apparatus further includes a plurality of hands which can hold one to five semiconductor wafers, which hands can be automatically exchanged into the lift arms.
In view of the above-mentioned problem in the conventional method, it is an object of the present invention to provide a method of fabricating a display panel and a method of relocating a display panel both of which are capable of enhancing a fabrication yield in fabrication of display panels, in particular, shortening time which a step of introducing liquid crystal into a space formed between substrates takes.
There is provided a method of fabricating a display panel, including a first step and a second step which is to be carried out immediately before the first step, the first step taking longer time to be carried out per a display panel than that of the second step, the number of display panels to be processed in the first step being greater than the number of display panels to be processed in the second step.
It is preferable that the first step includes the relocation step of relocating display panels into a first cassette used in the first step from a second cassette used in the second step in the greater number than the number of display panels having been processed in the second step.
For instance, the relocation step may be comprised of the steps of (a) upwardly taking a display panel out of a first cassette in which display panels are stored, with the display panel being supported at upper and lower edges thereof, (b) supporting the display panel taken out of the first cassette, at lower and side edges thereof, (c) laterally transferring the display panel from a position above the first cassette to a position above a second cassette, and (d) supporting the display panel at upper and side edges thereof and lowering the display panel into the second cassette.
It is preferable that the step (a) further includes the step of compensating for a pitch at an upper edge of the display panel when the display panel is supported at the upper edge thereof.
It is preferable that the step (a) further includes the step of compensating for a pitch at a side edge of the display panel when the display panel is supported at the side edge thereof.
For instance, the step (a) may further include the steps of (a1) transferring a first cassette including display panels, into a first station, (a2) taking the display panels out of the first cassette in the first station, and (a3) transferring the first cassette out of the first station, and the step (d) may further include the steps of (d1) transferring a second cassette including no display panels into a second station, (d2) introducing display panels into the second cassette, and (d3) transferring the second cassette out of the second station.
It is preferable that the first cassette is transferred in a first direction in a first stream line and the second cassette is transferred in a second direction in a second stream line, the first and second directions are opposite to each other, the first and second stream lines being spaced away from each other and being in parallel with each other.
It is preferable that the method further includes the step (e) of rotating the second cassette in a horizontal plane by 90 degrees, the step (e) being to be carried out before or after the step (d).
It is preferable that the method further includes the step (f) of rotating the first cassette in a horizontal plane by 90 degrees, the step (f) being to be carried out before or after the step (a).
It is preferable that the first and second cassettes have the same size.
It is preferable that each of the first and second cassettes is comprised of (a) a pair of frames, (b) a plurality of shafts extending between the frames, and (c) a pair of panel-supporting plates, at least one of the panel-supporting plates being slidable along the shafts and being able to be fixed at any position.
It is preferable that the first step is a step of introducing liquid crystal into a space formed between two substrates.
There is further provided a method of fabricating a display panel, including a first step and a second step which is to be carried out immediately after the first step, the first step taking longer time to be carried out per a display panel than that of the second step, the number of display panels to be processed in the first step being greater than the number of display panels to be processed in the second step.
There is still further provided a method of fabricating a display panel, including a first step, a second step which is to be carried out immediately before the first step, and a third step which is to be carried out immediately after the first step, the first step taking longer time to be carried out per a display panel than those of the second and third steps, the number of display panels to be processed in the first step being greater than both the number of display panels to be processed in the second step and the number of display panels to be processed in the third step.
There is yet further provided a method of fabricating a display panel, including a first step and a second step which is to be carried out immediately before the first step, the first step taking longer time to be carried out per a display panel than that of the second step, the number of display panels to be processed in the first step being greater than the number of display panels having been processed in the second step.
There is still yet further provided a method of fabricating a display panel, including a first step and a second step which is to be carried out immediately after the first step, the first step taking longer time to be carried out per a display panel than that of the second step, the number of display panels to be processed in the first step being greater than the number of display panels to be introduced into the second step.
There is further provided a method of fabricating a display panel, including a first step, a second step which is to be carried out immediately before the first step, and a third step which is to be carried out immediately after the first step, the first step taking longer time to be carried out per a display panel than those of the second and third steps, the number of display panels to be processed in the first step being greater than both the number of display panels having been processed in the second step and the number of display panels to be introduced into the third step.
There is further provided a method of relocating display panels, including the steps of (a) upwardly taking a display panel out of a first cassette in which display panels are stored, with the display panel being supported at upper and lower edges thereof, (b) supporting the display panel taken out of the first cassette, at lower and side edges thereof, (c) laterally transferring the display panel from a position above the first cassette to a position above a second cassette, and (d) supporting the display panel at upper and side edges thereof and lowering the display panel into the second cassette.
The advantages obtained by the aforementioned present invention will be described hereinbelow.
In accordance with the present invention, it is possible in fabrication of a liquid crystal display panel, for instance, to process liquid crystal display panels in a step of introduction of liquid crystal by the unit number greater than both the unit number of liquid crystal display panels in a step of dicing, which is to be carried out immediately before the step of introduction of liquid crystal, and the unit number of liquid crystal display panels in a step of sealing, which is to be carried out immediately after the step of introduction of liquid crystal.
It is also possible to relocate display panels with high efficiency.
Hence, even if a conventional fabrication line is used as it is, it would not be necessary to increase the number of apparatuses for introducing liquid crystal into a space formed between substrates, and the fabrication line and other fabrication steps are not necessary to be modified. Hence, it would be possible to enhance an efficiency in fabrication steps of a liquid crystal display panel and in a fabrication line.
The above and other objects and advantageous features of the present invention will be made apparent from the following description made with reference to the accompanying drawings, in which like reference characters designate the same or similar parts throughout the drawings.